There are a variety of situations in which passengers, troops, or vehicles must be transferred from a ship to a shoreline or vice versa. Examples of vessels that engage in this operation include roll-on/roll-off vehicle ferries and naval logistics support vessels.
The transfer requires a device that holds the ship near the shoreline and some way for passengers, vehicles, etc. to offload or onload. Offloading and onloading is typically performed using a ramp. The ramp and the holding/stabilizing device are collectively referred to as an “interface.” Usually, some portion of the interface is carried by the ship (“the shipside interface”) and some portion is located on the shore (“the shoreside interface”).
The interface must maintain vessel position and yaw angle during offloading and onloading operations. And it must permit the vessel to resist wave, current and wind forces while accommodating pitch and heave due to tides and the transfer of vehicles.
The conventional approach to the ship-to-shore interface has been to provide a simple vehicle ramp on the shipside and to construct elaborate shoreside facilities to guide, position, and hold the vessel to the shore. But this approach has several drawbacks.
In particular, having an elaborate shoreside facility equates to high harbor infrastructure costs. Furthermore, extensive shoreside interface facilities can have a deleterious impact on the surrounding environs. For military applications, landing forces are often required to rapidly offload on unimproved or semi-improved beachheads. For such applications, an elaborate shoreside facility is not possible.
As a consequence, there is a need for an interface that is capable of creating a temporary connection between a ship and a shoreline that:                is mechanically simple on both the shipside and the shoreside; and        is capable of controlling vessel surge, sway, roll, and pitch.        